which sense modality is slowest to adapt?

signal detection theory

our ability to detect a sensory stimulus (signal) depends not only on the intensity of the signal but also on variables such as distractions and motivation

no such thing as an absolute threshold for a given stimulus modality because detecting a signal depends not only on stimulus strength but also on background noise and psychological variables such as expectation and response bias

Is depth perception an innate ability or learned?

size constancy

1 form of perceptual constancy

although the retinal image of an object becomes smaller as the object recedes into the distance (or larger as it approaches), the viewer adjusts for this change and perceives the object to be constant in size

A.H Holway and Edwin Boring (1941)

performed classic study of size constancy that found that subjects were able to make extremely accurate judgments of the size of a circle located at varying distances under conditions filled with distance cues

As distance cues were eliminated, judgment of size became dependent on the size of the retinal image

conclusion was that that an important cue for size constancy is retinal size

R.L. Gregory

moon illusion

when moon is low on the horizon,it appears larger than when it is overhead, yet the actual size of the moon's image on the retina is the same regardless of position in sky.illusion result of size constancy.

when moon is low, it appears to be farther away than when it is overhead. this effect results from visual cues for distance. compared to trees and other objects on the horizon, we perceive moon to be far away. when we look at the moon overhead, we have no visual cues for distance

ponzo illusion

poggendorf illusion

appears that if the diagonal line were continued toward each other, the one on the right would pass above the left line. in reality, they would join. results from our inclination to maintain shape constancy